The present invention relates generally to two-cycle engines and more particularly to certain new and useful improvements in the intake, upper cylinder charging and the exhaust systems of two-cycle engines which may be manufactured at low cost with relatively few and substantially simple operating parts, while increasing engine life and offering more efficient and consistent power outputs at high and low speeds and high and low compression than in two-cycle engines heretofore known. As will become evident from the description of the invention, the invention has applicability to two-cycle engines wherein combustion is effected by either electrical spark or diesel effect.
Previously known two-cycle engines generally comprise cylinder housings enclosing one or more engine cylinders, each formed with a fuel transfer passage external of the cylinder to provide an access conduit for transferring fuel, which has been compressed in the crankcase, from the crankcase into the combustion chamber. Each engine cylinder contains a piston, slidable therein, which is generally formed with a port in its side for registering with one end of the fuel transfer passage to allow flow into the combustion chamber. In accordance with some of these known engine configurations, when the piston port and transfer passage are in registration, either in whole or in part, fuel passes from the passage into the piston itself for discharge into the combustion chamber through an open nozzle in the piston. In accordance with other known engine constructions, when the piston port and transfer passage are in registration, fuel flows from the piston port into the entrance of the transfer passage which exits in the combustion chamber.
Although these known engine constructions have proved adequate for low speed operation and low compression adaptations, the complexity of the cylinder, housing and piston structures necessitates multiple and intricate fabrication techniques to which high manufacturing costs are attributable. Furthermore, these engines experience significant flow losses in charging the combustion chamber and have a relatively low efficiency and power output. For example, the relatively short period of time that the piston port and transfer passage are in registration-either in whole or in part-as well as the dimensions of the fuel transfer passage limit the charging of the combustion chamber such that reliable and proper charging cannot be assured. Furthermore, the piston structures are generally heavy or provided with very complex surfaces, thereby reducing the output of the engine. These considerations are significant in reducing power output and preventing higher efficiency, especially at high speed operation or in high compression operation adaptations.
Other known two-cycle engine constructions are provided with pistons formed with projections or other irregular structures protruding into the combustion chamber to guide incoming flow from transfer or bypass channels. Such structures complicate fabrication and are susceptible to damaging as a result of local overheating, thereby shortening the useful life of the engine.
One prior art two-cycle engine construction utilizes a piston formed with an inlet port on its top surface, controlled by a pressure operated valve. An example of this engine is disclosed in U.S. Pat. No. 1,082,402 to Campbell. Although such engines may offer certain advantages, they are usually complicated with cams, lifters and heavy spring-loaded valves. Consequently, these engines have not proved to be efficient and generally suffer from power output losses, especially at high speed and/or high compression operation.
However, none of these known constructions provide for introducing an adequate charge for combustion into the combustion chamber throughout their range of operation. Moreover, no two-cycle engine has been developed which provides a mechanically simple and relatively inexpensive means for assuring proper and reliable charging of the combustion chamber in engines operating at high and low speeds and high and low compression, to generate consistently high efficiency and high power output in all such ranges of operation. Furthermore, no two-cycle engine has been eveloped which is capable of long life and extended use in high speed and/or high compression applications.
It is therefore an object of the present invention to provide a new and improved two-cycle engine.
It is another object of the present invention to provide an improved fuel and/or air intake, charge introduction and exhaust system in two-cycle engines.
It is still another object of this invention to provide a mechanically simple two-cycle engine capable of higher power output and efficiency than heretofore achieved.
It is also an object of this invention to provide a new two-cycle engine capable of easy and inexpensive fabrication.
It is still another object of the present invention to provide a new piston assembly for use in two-cycle engines, which controls the fuel and/or air intake, the introduction of a fresh charge into the combustion chamber and the exhaust of burned gases.
It is also an object of the present invention to provide a charge introduction system for use in two-cycle engines whereby the piston is cooled to allow use for extended periods of time.
It is yet another object of the present invention to provide a light piston for higher output and efficiency than heretofore achieved in two-cycle engines.
It is a further object of the present invention to provide a two-cycle engine free from extra-cylinder air or air/fuel passages.
It is another object of the present invention to provide a two-cycle engine having relatively few moving parts.
It is yet another object of the present invention to provide a two-cycle engine wherein fuel is evaporated to ensure good mixture formation while the piston is simultaneously cooled.
It is still another object of the present invention to provide a two-cycle engine capable of efficiently generating reliable power output at high and low speeds of operation and high and low compression.
It is yet a further object of the present invention to provide a structurally simple two-cycle engine capable of use for extended periods of time at high speed and/or high compression operation.
These and other objects, features and advantages of the present invention will become more apparent when the detailed description of the preferred embodiments is considered in light of the drawings.
The invention consists of the novel parts, constructions, arrangements, combinations and improvements herein shown and described.